Smoke retardant vinyl chloride and vinylidene chloride polymer compositions

ABSTRACT

Smoke retardant vinyl chloride and vinylidene chloride polymer compositions are obtained by including therein a synergistic mixture of (A) at least one nickel compound selected from the group consisting of Ni(BO 2 ) 2 , Ni 2  O.sub. 3, Ni 3  (PO 4 ) 2 , nickel citrate, nickel oxalate and tetrakis(triphenyl phosphite)nickel, and (B) at least one aluminum compound selected from the group consisting of aluminum metal, γ-Al 2  O 3 , AlSb, aluminum zinc sulfate, basic aluminum acetate and sodium aluminum carbonate (dawsonite). Substantial smoke retardation is also obtained by including the above nickel compounds or aluminum compounds individually in the vinyl chloride or vinylidene chloride polymer compositions, except for tetrakis (triphenyl phosphite) nickel.

BACKGROUND OF THE INVENTION

Vinyl chloride and vinylidene chloride polymers are known to beself-extinguishing and relatively more flame retardant than otherpolymers such as polyethylene, polypropylene and the like. However, asubstantial amount of smoke may be produced upon exposure of vinylchloride and vinylidene chloride polymers to a flame. Convention flameretardants such as antimony oxide do not aid in smoke reduction.

The following art is related to the present invention. Salts or oxidesof nickel or aluminum are effective in amounts up to several percent ascondensing agents for polyvinyl halides (U.S. Pat. No. 2,157,997). Priorart such as U.S. Pat. No. 3,107,106 teaches use of aluminum metal inpolyvinyl chloride compositions. Smoke- and flame-retardant compositionsare known which contain dawsonite (U.S. Pat. No. 3,869,420 and Ger. Pat.No. 2,363,311). Aluminum oxides can be used together with othermaterials in a flame-proofing composition (U.S. Pat. No. 2,610,920). Thefact that an additive is a flame retardant does not necessarily meanthat it will have good smoke retardant properties, as is well known tothose skilled in the art. New smoke retardant vinyl chloride andvinylidene chloride polymer compositions are desired.

SUMMARY OF THE INVENTION

Smoke retardant vinyl chloride and vinylidene chloride polymercompositions are obtained by including therein a synergistic mixture of(A) at least one nickel compound selected from the group consisting ofNi(BO₂)₂, Ni₂ O₃, Ni₃ (PO₄)₃, nickel citrate, nickel oxalate andtetrakis (triphenyl phosphite) nickel, and (B) at least one aluminumcompound selected from the group consisting of aluminum metal, γ-Al₂ O₃,AlSb, aluminum zinc sulfate, basic aluminum acetate, and sodium aluminumcarbonate (dawsonite). Substantial smoke retardation is also obtained byincluding these aluminum compounds individually in the vinyl chloride orvinylidene chloride polymer compositions: nickel oxalate, AlSb, aluminumzinc sulfate and basic aluminum acetate.

DETAILED DESCRIPTION

The following compounds are novel as additives in vinyl chloride andvinylidene chloride polymer compositions and are effective individuallyas smoke retardants: nickel oxalate, AlSb, aluminum zinc sulfate andbasic aluminum acetate. Moreover, the present invention also encompassesvinyl chloride and vinylidene chloride polymer compositions containingtherein synergistic mixtures of (A) at least one nickel compoundselected from the group consisting of Ni(BO₂)₂, Ni₂ O₃, Ni₃ (PO₄)₃,nickel citrate, nickel oxalate and tetrakis (triphenyl phosphite)nickel, and (B) at least one aluminum compound selected from the groupconsisting of aluminum metal, γ-Al₂ O₃, AlSb, aluminum zinc sulfate,basic aluminum acetate and sodium aluminum carbonate (dawsonite).

Vinyl chloride and vinylidene chloride polymers used in this inventioninclude homopolymers, copolymers and blends of homopolymers and/orcopolymers. The vinyl chloride and vinylidene chloride polymers maycontain from 0 up to about 50% by weight of at least one otherolefinically unsaturated monomer, more preferably at least one othervinylidene monomer (i.e. monomer containing at least one terminal CH₂=C< group per molecule) copolymerized therewith, more preferably up toabout 20% by weight of such monomer. Suitable monomers include 1-olefinscontaining from 2 to 12 carbon atoms, more preferably from 2 to 8 carbonatoms, such as ethylene, propylene, 1-butene, isobutylene, 1-hexene,4-methyl-1-pentene and the like; dienes containing from 4 to 10 carbonatoms including conjugated dienes as butadiene, isoprene, piperylene andthe like; ethylidene norbornene and dicyclopentadiene; vinyl esters andallyl esters such as vinyl acetate, vinyl chloroacetate, vinylpropionate, vinyl laurate, allyl acetate and the like; vinyl aromaticssuch as styrene, α-methyl styrene, chlorostyrene, vinyl toluene, vinylnaphthalene and the like; vinyl and allyl ethers and ketones such asvinyl methyl ether, allyl methyl ether, vinyl isobutyl ether, vinyln-butyl ether, vinyl chloroethyl ether, methyl vinyl ketone and thelike; vinyl nitriles such as acrylonitrile, methacrylonitrile and thelike; cyanoalkyl acrylates such as α-cyanomethyl acrylate, the α-, β-and γ- cyanopropyl acrylates and the like; olefinically unsaturatedcarboxylic acids and esters thereof, including α,β-olefinicallyunsaturated acids and esters thereof such as methyl acrylate, ethylacrylate, chloropropyl acrylate, butyl acrylate, hexyl acrylate,2-ethyl-hexyl acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexylacrylate, phenyl acrylate, glycidyl acrylate, methoxyethyl acrylate,ethoxyethyl acrylate, hexylthioethyl acrylate, methylmethacrylate, ethylmethacrylate, butyl methacrylate, glycidyl methacrylate and the like,and including esters of maleic and furmaric acid and the like; amides ofthe α,β-olefinically unsaturated carboxylic acids such as acrylamide andthe like; divinyls, diacrylates and other polyfunctional monomers suchas divinyl benzene, divinyl ether, diethylene glycol diacrylate,ethylene glycol dimethacrylate, methylene-bis-acrylamide, allylpentaerythritol, and the like; bis(βhaloalkyl)alkenyl phosphonates suchas bis(β-chloroethyl) vinyl phosphonate and the like; and the like.

More preferred monomers include 1-olefins containing from 2 to 12 carbonatoms, more preferably from 2 to 8 carbon atoms, such as ethylene,propylene, 1-butene, isobutylene, 1-hexene, 4-methyl-1-pentene and thelike; vinyl esters and allyl esters such as vinyl acetate, vinylchloroacetate, vinyl propionate, vinyl laurate, allyl acetate and thelike; olefinically unsaturated carboxylic acids and esters thereof,including α,β-olefinically unsaturated acids and esters thereof such asmethyl acrylate, ethyl acrylate, chloropropyl acrylate, butyl acrylate,hexyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecylacrylate, cyclohexyl acrylate, phenyl acrylate, glycidyl acrylate,methoxyethyl acrylate, ethoxyethyl acrylate, hexylthioacrylate, methylmethacrylate, ethyl methacrylate, butyl methacrylate, glycidylmethacrylate and the like, and including esters of maleic and fumaricacid and the like; and amides of α,β-olefinically unsaturated carboxylicacids such as acrylamide and the like.

More preferred smoke retardant synergistic mixtures include a mixture of(A) nickel oxalate and (B) aluminum zinc sulfate. Nickel oxalate is amore preferred individual smoke retardant additive. Supporting mediasuch as SiO₂ and other substantially inert inorganic supportingmaterials known in the art may be used for the smoke retardant additivesand in many cases are preferred, since additive surface area is greatlyincreased for smoke reduction purposes.

Not all nickel compound/aluminum compound mixtures are synergistic, andit is difficult or impossible to predict synergism. Mixtures found to benonsynergistic include NiO and aluminum ammonium sulfate, NiO andaluminum potassium sulfate, NiO and aluminum acetylacetonate, NiO andAlPO₄, NiO and basic aluminum acetate, NiO and AlSb, NiO and Al₂(SO₄)₃.18H₂ O, NiO and aluminum metal, and NiO and γ-Al₂ O₃. Othernonsynergistic combinations include nickel metal and aluminum ammoniumsulfate, NiS and Al₂ (SO₄)₃.18H₂ O, NiSO₄ and aluminum potassiumsulfate, NiWO₄ and aluminum acetylacetonate, Ni₂ Si and AlPO₄, NiCrO₄and Al₂ (MoO₄)₃, NiB₂ and hydrated alumina, nickel formate and Al₂(SO₄)₃.18H₂ O, and NiSnO₃ and aluminum stearate. Moreover,tetrakis(triphenyl phosphite) nickel was found to increase smokeformation in polyvinyl chloride compositions. Thus, it was surprisingand unexpected to find smoke reduction using nickel oxalate or thespecific nickel compound/aluminum compound mixtures of this invention.

The additive compounds used in this invention are polycrystalline oramorphous fine powders, preferably with an average particle size lessthan about 200 microns, more preferably from about 0.5 to about 150microns. Polymer compositions containing the additives may have colorssimilar to, although somewhat lighter than, the additives themselves.The additive compounds are used in total amounts from about 0.01 toabout 100 parts by weight, more preferably from about 0.01 to about 20parts by weight, per 100 parts by weight of polymer. Use of more thanabout 100 parts by weight of additive per 100 parts by weight of polymerprobably will affect adversely other important physical properties, suchas tensile strength and the like.

The vinyl chloride and vinylidene chloride polymers may be prepared byany method known to the art such as by emulsion, suspension, bulk orsolution polymerization. The additive compounds may be mixed with thepolymer emulsion, suspension, solution or bulk mass before monomerrecovery and/or drying. More preferably the compounds may be mixed withdry granular or powdered polymers. The polymer and compound may be mixedthoroughly in granular or powder form in apparatus such as a Henschelmixer and the like. Alternatively, this step may be eliminated and themixing done while the polymer mass is fluxed, fused and masticated tohomogeneity under fairly intensive shear in or on a mixer apparatushaving its metal surface in contact with the material. The fusiontemperature and time will vary according to the polymer composition andlevel of additive compound but will generally be in the range of about300 to 400°F and 2 to 10 minutes.

Smoke retardancy may be measured using a NBS Smoke Chamber according toprocedures described by Gross et al, "Method for Measuring Smoke fromBurning Materials", Symposium on Fire Test Methods - Restraint & Smoke1966, ASTM STP 422, pp. 166-204. Maximum smoke density (D_(m)) is adimensionless number and has the advantage of representing a smokedensity independent of chamber volume, specimen size or photometer pathlength, provided a consistent dimensional system is used. Maximum rateof smoke generation (R_(m)) is defined in units of min.⁻ ¹. Percentsmoke reduction is calculated using this equation: ##EQU1## The term"D_(m) /g" means maximum smoke density per gram of sample. D_(m) andother aspects of the physical optics of light transmission through smokeare discussed fully in the above ASTM publication.

Smoke retardance may be measured quickly using the Goodrich Smoke-CharTest. Test samples may be prepared by dry blending polymer resin andsmoke retardant additives. The blend is ground in a liquid N₂ -cooledgrinder to assure uniform dispersion of the smoke retardant additives inthe resin. Small (about 0.3 g) samples of the polymer blend are pressedinto pellets about 1/4 inch in diameter for testing. Alternatively, testsamples may be prepared by blending resin, smoke retardant additives andlubricant(s) or processing aid(s) in a blender such as an Osterizerblender. The blend is milled, pressed into sheets, and cut into small(about 0.3 gram) samples for testing. The test samples are placed on ascreen and burned for 60 seconds with a propane gas flame risingvertically from beneath the sample. Sample geometry at a constant weighthas been found not to be significant for the small samples used in thistest. A Bernz-O-Matic pencil flame burner head is used with gas pressuremaintained at 40 psig. The sample is immersed totally and continuouslyin the flame. Smoke from the burning sample rises in a vertical chimneyand passes through the light beam of a Model 407 Precision WidebandPhotometer (Grace Electronics, Inc., Cleveland, Ohio) coupled with aphotometer integrator. Smoke generation is measured as integrated areaper gram of sample.

The vinyl chloride and vinylidene chloride polymer compositions of thisinvention may contain the usual compounding ingredients known to the artsuch as fillers, stabilizers, opacifiers, lubricants, processing aids,impact modifying resins, plasticizers, antioxidants and the like.

The following examples illustrate the present invention more fully.

    ______________________________________                                        EXAMPLES 1-6                                                                  The following recipe was used:                                                MATERIAL             PARTS                                                    ______________________________________                                        Polyvinyl Chloride*  100.0                                                    Additive (A)**       Variable                                                 Additive (B)***      Variable                                                 ______________________________________                                          *Homopolymer having an inherent viscosity of about 0.92-0.99; ASTM           Classification GP-4-15443.                                                     **Nickel compound selected from the group consisting of                      Ni(BO.sub.2).sub.2, Ni.sub.2 O.sub.3, Ni.sub.3 (PO.sub.4).sub.2, nickel       citrate, nickel oxalate and tetrakis(triphenyl phosphite) nickel. The         control sample contained no additive.                                         ***Aluminum compound selected from the group consisting of aluminum metal     γ-Al.sub.2 O.sub.3, AlSb, aluminum zinc sulfate, basic aluminum         acetate, and sodium aluminum carbonate (dawsonite). The control sample        contained no additive.                                                   

Each experimental sample was prepared by blending resins and additivesin a liquid N₂ -cooled grinder to assure uniform dispersion of the smokeretardant additives in the resin. Small (about 0.3 gram) samples of thepolymer blend were pressed into pellets about 1/4 inch in diameter andtested using the Goodrich Smoke-Char Test described heretofore. Testresults are given in Table I.

                                      TABLE I                                     __________________________________________________________________________         Additive (A) Additive (B)     Smoke Formation                                                                          Reduction                       Ex.    (phr)        (phr)          per Gram of Sample                                                                       (%)                             __________________________________________________________________________    Control                                                                            None         None             67.4       --                              1    Ni(BO.sub.2).sub.2 (10)                                                                     --              56.8       16                                    --          Basic Aluminum acetate (10)                                                                    41.9       38                                   Ni(BO.sub.2).sub.2 (5)                                                                     Basic Aluminum acetate (5)                                                                     36.2       46                              2    Ni.sub.2 O.sub.3 (10)                                                                       --              47.0       30                                    --          Sodium aluminum carbonate (10)                                                                 41.2       39                                   Ni.sub.2 O.sub.3 (5)                                                                       Sodium aluminum carbonate (5)                                                                  34.7       49                              3    Ni.sub.3 (PO.sub.4).sub.2 (10)                                                              --              45.5       32                              Al.sub.2 O.sub.3 (10)mma.                                                          39.7         41                                                               Ni.sub.3 (PO.sub.4).sub.2 (5)                                                              γ-Al.sub.2 O.sub.3 (5)                                                                   34.0       50                              4    Nickel citrate (10)                                                                         --              41.8       38                                    --          AlSb (10)        57.3       15                                   Nickel citrate (5)                                                                         AlSb (5)         36.0       47                              5    Nickel oxalate (10)                                                                         --              28.1       58                                    --          Aluminum zinc sulfate (10)                                                                     37.2       45                                   Nickel oxalate (5)                                                                         Aluminum zinc sulfate (5)                                                                      16.6       75                              6    Tetrakis (triphenyl                                                           (phosphite)nickel (10)                                                                      --              77.9       15% increase                          --          Aluminum metal (10)                                                                            66.9        1                                   Tetrakis (triphenyl                                                           phosphite)nickel (5)                                                                       Aluminum metal (5)                                                                             47.3       30                              __________________________________________________________________________

These results demonstrate that the defined additive mixturessubstantially reduce smoke evolution during forced burning of rigidpolyvinyl chloride in the Goodrich Smoke-Char Test. The results alsodemonstrate the smoke retardant effects of individual additives in thesame test, except for tetrakis (triphenyl phosphite) nickel.

The improved smoke retardant vinyl chloride and vinylidene chloridepolymer compositions of this invention are useful wherever smokeresistance is desirable, such as in carpets, house siding, plasticcomponents for airplane interiors, and the like. Of course, overallsuitability for a particular use will depend upon other factors as well,such as comonomer type and level, compounding ingredient type and level,polymer particle size, and the like.

I claim:
 1. A smoke retardant composition comprising a vinyl chloride orvinylidene chloride polymer together with (A) at least one nickelcompound selected from the group consisting of Ni(BO₂)₂, Ni₂ O₃, Ni₃(PO₄)₂, nickel citrate, nickel oxalate and tetrakis (triphenylphosphite) nickel and (B) at least one aluminum compound selected fromthe group consisting of aluminum metal, γ-Al₂ O₃, AlSb, aluminum zincsulfate, basic aluminum acetate, and sodium aluminum carbonate(dawsonite), said compounds (A) and (B) being present in a total amountfrom about 0.25 to about 100 weight parts per 100 weight parts ofpolymer.
 2. A composition of claim 1 wherein said polymer containscopolymerized therewith up to about 50% by weight of at least one otherolefinically unsaturated monomer.
 3. A composition of claim 2 whereinsaid polymer contains copolymerized therewith up to about 20% by weightof said other monomer.
 4. A composition of claim 3 wherein said othermonomer is selected from the group consisting of 1-olefins containingfrom 2 to 12 carbon atoms, vinyl esters, α,β-olefinically unsaturatedcarboxylic acids and esters thereof, amides of α,β-olefinicallyunsaturated carboxylic acids, and esters of fumaric and maleic acid. 5.A composition of claim 4 wherein said compound has an average particlesize less than about 200 microns.
 6. A composition of claim 5 whereinsaid compound (A) is Ni(BO₂)₂ and said compound (B) is basic aluminumacetate.
 7. A composition of claim 5 wherein said compound (A) is Ni₂ O₃and said compound (B) is sodium aluminum carbonate.
 8. A composition ofclaim 5 wherein said compound (A) is Ni₃ (PO₄)₂ and said compound (B) isγ-Al₂ O₃.
 9. A composition of claim 5 wherein said compound (A) isnickel citrate and said compound (B) is AlSb.
 10. A composition of claim5 wherein said compound (A) is nickel oxalate and said compound (B) isaluminum zinc sulfate.
 11. A composition of claim 5 wherein saidcompound (A) is tetrakis (triphenyl phosphite) nickel and said compound(B) is aluminum metal.
 12. A smoke retardant composition comprising avinyl chloride or vinylidene chloride polymer together with at least onecompound selected from the group consisting of nickel oxalate, AlSb,aluminum zinc sulfate and basic aluminum acetate, said compound beingpresent in an amount from about 0.25 to about 100 weight parts per 100weight parts of polymer.
 13. A composition of claim 12 wherein saidpolymer contains copolymerized therewith up to about 50% by weight of atleast one olefinically unsaturated monomer.
 14. A composition of claim13 wherein said polymer contains copolymerized therewith up to about 20%by weight of said other monomer.
 15. A composition of claim 14 whereinsaid other monomer is selected from the group consisting of 1-olefinscontaining from 2 to 12 carbon atoms, vinyl esters α,β-olefinicallyunsaturated carboxylic acids and esters thereof, amides ofα,β-olefinically unsaturated carboxylic acids, and esters of fumaric andmaleic acid.
 16. A composition of claim 15 wherein said compound has anaverage particle size less than about 200 microns.
 17. A composition ofclaim 16 wherein said compound is nickel oxalate.
 18. A composition ofclaim 16 wherein said compound is AlSb.
 19. A composition of claim 16wherein said compound is aluminum zinc sulfate.
 20. A composition ofclaim 16 wherein said compound is basic aluminum acetate.